French prosecutors have announced they will investigate Renault over suspected “cheating” in emissions tests of diesel motors, causing shares in the carmaker to fall.

Following a massive emissions scandal involving Volkswagen, independent French experts found dangerously high levels of emissions from diesel engines of several carmakers, including Renault, the Paris prosecutors office said on Friday.

Prosecutors have ordered an investigation into “cheating on key parts (of vehicles)” and into the quality of the tests carried out.

The Italian-American company immediately denied the charges and pledged to work with president-elect Donald Trump’s administration to resolve the issue “fairly”.

The UK has lodged an urgent request with US authorities for information on the allegations against Fiat Chrysler.

The US Environmental Protection Agency said undisclosed software on the 2014 to 2016 models of Grand Cherokees and Dodge Ram 1500 trucks allowed the vehicles to emit more nitrogen oxides than permitted.

The US justice department also charged six Volkswagen executives deemed responsible for the conspiracy, five of whom are believed to be in Germany with one arrested in Miami on Saturday.

Earlier this week a group of 10,000 UK VW owners filed a class action lawsuit against the German car firm, seeking £30m, or £3,000 each.

The chair of a parliamentary committee on the environment and consumer group Which? both welcomed the claim, which VW said it would “robustly” contest.

If the company had to pay £3,000 to each of the 1.2 million people who own affected cars, including its Škoda, Audi and Seat marques, it would cost about £3.6bn.

The German firm has yet to reach a settlement with British and European owners affected by the scandal, in which the company admitted using “defeat devices” to cheat emissions tests, making its cars appears greener than they were.